JP2004187237A - Base station device, and packet transmission scheduling method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce deterioration of throughput and to reduce entire buffer amount by appropriately controlling the data storage amount of a queue for temporarily storing a packet. <P>SOLUTION: A priority queue 11 notifies a remaining buffer capacity measuring part 112 of the data storage situation of the queue wherein a transmitting packet is stored. The remaining buffer capacity measuring part 112 measures remaining buffer capacity from the reported information and outputs the result to a scheduler 113. The scheduler 113 acquires a reception quality of a mobile station from a demodulation part 107, calculates priority (=reception quality×1/remaining buffer capacity) for each packet and selects a queue wherein the packet of the highest priority is stored. Further, according to the priority, transmission conditions such as modulation scheme and encoding rate are determined and circuits such as a HARQ part 116 and modulation part 103 are controlled. A switch 114 changes over outputs of the priority queue 111. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a base station apparatus that controls a queue (buffer) for temporarily storing transmission packets, and a packet transmission scheduling method used in the base station apparatus.
[0002]
[Prior art]
Conventionally, as a higher-speed IMT-2000 packet transmission method, a method called HSDPA (High Speed Downlink Packet Access) for the purpose of increasing the downstream peak transmission speed, reducing the transmission delay, and increasing the throughput has been studied. I have.
[0003]
In this high-speed packet radio communication system, services by various applications such as voice, video, data transmission, and the like are expected. Therefore, a packet control technique in consideration of various QoS (Quality of Service) requirements is indispensable. Incidentally, the QoS request value includes an error rate, an allowable delay time, a transmission rate, a fluctuation, a packet discard rate, and the like requested from an upper layer. A base station adopting the HSDPA scheme has a queue (buffer) for temporarily storing a packet to be transmitted to a mobile station for each QoS, identifies a QoS of a packet transmitted from a higher-level station, and sets a corresponding queue. To store the packet.
[0004]
The exchange of the queue capacity management (flow control) is performed by the MAC-hs units of the upper station and the base station. By the flow control, when the number of packets stored in the queue is small, more packets are transmitted to the base station and stored in this queue, and when the number of packets stored in the queue is large, it is defined in advance. The amount of packets to be transmitted to the base station is reduced and the amount of data in the queue is controlled so as not to exceed the upper limit of the buffer amount of the queue (the specified queue amount). The MAC-hs unit of the base station notifies the upper station of the amount of data stored in the queue or the free space of the buffer.
[0005]
On the other hand, there is a technique called scheduling that determines the priority of a packet transmitted from a base station to a mobile station as one that affects the capacity of the queue (for example, see Non-Patent Document 1). Scheduling is a technique for deciding which mobile station is to be assigned a downlink, and performs control to determine a priority in transmission of a packet in one or a plurality of transmission buffers. The amount of data in the queue also changes depending on the result of this scheduling.
[0006]
[Non-patent document 1]
IEICE Technical Report MoMuC2002-3 (2002-05), IEICE
[0007]
[Problems to be solved by the invention]
However, when a large number of packets are stored in the queue, the conventional base station apparatus performs flow control with an upper station so that data does not overflow. However, there is a time lag before the control information is transmitted to the upper station and the packet flow is actually controlled, and there is a problem that data overflowed during this time is discarded. When the data is discarded, the data is retransmitted by the upper station, and the throughput is deteriorated. Also, in consideration of this time lag, a method of securing an extra buffer (memory) of (time lag) × (maximum transmission rate of data from the upper station) in order to absorb a surplus input transmitted from the upper station. However, there is a problem that the circuit scale becomes large.
[0008]
SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to appropriately control the data storage amount of a queue for temporarily storing packets to prevent a decrease in throughput and reduce the overall buffer amount. It is an object of the present invention to provide a base station apparatus and a packet transmission scheduling method capable of performing the above. It is another object of the present invention to reduce the processing calculation amount and the processing time of the packet transmission scheduling and increase the throughput of the communication system.
[0009]
[Means for Solving the Problems]
The base station apparatus of the present invention is a base station that performs packet transmission scheduling when transmitting a packet to a mobile station, and a buffer for temporarily storing a packet to be transmitted to the mobile station, based on the free space of the buffer, Priority calculating means for calculating the priority of the packet used when performing the packet transmission scheduling.
[0010]
A base station apparatus according to the present invention is a base station that performs packet transmission scheduling when transmitting a packet to a mobile station, a buffer for temporarily storing a packet to be transmitted to the mobile station, and a line between the own station and the mobile station. Line quality acquisition means for acquiring quality, and priority calculation means for calculating the priority of the packet used when performing the packet transmission scheduling, based on the free space of the buffer and the acquired line quality, Is adopted.
[0011]
According to these configurations, it is possible to preferentially transmit packet data to a queue having a large amount of data stored in the queue by reflecting the buffer remaining amount in the priority, and the upper limit of the specified queue amount By transmitting the packet data in the queue before the number of packets reaches, the total buffer amount can be reduced. Furthermore, by considering channel quality, transmission can be preferentially assigned to UEs with good propagation characteristics, so that the throughput of the communication system can be increased. However, for UEs that are not allocated due to poor propagation characteristics or have a large permissible time limit and that have a large amount of packet data stored in the queue, priority is given to transmission by taking into account the remaining buffer capacity. Can be assigned, and the fairness among users can be improved as compared with the case where the priority is calculated only by the channel quality.
[0012]
The base station apparatus of the present invention, in the above configuration, employs a configuration in which the priority calculating means calculates the priority of the packet further based on a remaining time with respect to a transmission allowable delay time of the packet.
[0013]
According to this configuration, in addition to the above-described operation, it also has an operation of increasing the priority of a packet such as data having a strong real-time property, so that it is possible to control the data storage amount of the queue and realize packet transmission scheduling that easily satisfies the QoS. it can. In addition, since the priority in consideration of QoS can be uniformly determined by a simple algorithm, it is possible to reduce the processing calculation amount and the processing time of the packet transmission scheduling.
[0014]
The base station apparatus according to the present invention, in the above configuration, employs a configuration in which the priority calculating means calculates the priority of the packet based further on a throughput of a line between the own station and the mobile station.
[0015]
According to this configuration, in addition to the above operation, there is also an operation of increasing the priority of a packet to a mobile station having a small actual throughput, so that it is easy to control the amount of data stored in the queue and to satisfy the fairness of the throughput between mobile stations. Packet transmission scheduling can be realized.
[0016]
The base station apparatus of the present invention, in the above configuration, employs a configuration in which the priority calculating means calculates the priority of the packet higher as the free space in the buffer is smaller.
[0017]
According to this configuration, the priority is calculated to be higher as the remaining amount of the buffer in the queue becomes smaller, so that the possibility that the packet is discarded can be reduced.
[0018]
The base station apparatus of the present invention, in the above configuration, employs a configuration in which the priority calculating means calculates the priority of the packet exponentially higher as the free space of the buffer is closer to zero.
[0019]
According to this configuration, when the remaining buffer capacity of the queue is likely to be exhausted, the priority is calculated higher, so that the possibility of packet discarding can be further reduced.
[0020]
The base station apparatus of the present invention, in the above configuration, employs a configuration in which the priority calculating means calculates the priority of the packet using a ratio between the free space of the buffer and the acquired line quality.
[0021]
According to this configuration, the algorithm of the packet transmission scheduling can be simplified, and the transmission of the communication system can be increased by allocating the transmission preferentially to UEs having good propagation characteristics.
[0022]
The base station apparatus of the present invention, in the above configuration, further comprising a weighting unit that weights the free space of the buffer, wherein the priority calculating unit is configured to calculate the priority based on the weighted free space of the buffer. A configuration for calculating the priority of a packet is employed.
[0023]
According to this configuration, in the priority calculation, the contribution of the control of the data storage amount of the queue can be adjusted, so that the control of the data storage amount of the queue and the other packet transmission scheduling are operated in harmony. be able to.
[0024]
The base station apparatus of the present invention, in the above configuration, may be configured such that the priority calculating means calculates the priority of the packet based on the amount of data stored in the buffer instead of the free space of the buffer. take.
[0025]
According to this configuration, it is possible to preferentially transmit a packet from a buffer having a large stored data amount.
[0026]
According to the packet transmission scheduling method of the present invention, the priority of the packet used for performing the packet transmission scheduling is calculated based on the free space of a buffer for temporarily storing the packet transmitted from the base station to the mobile station. A priority calculation step is provided.
[0027]
A packet transmission scheduling method according to the present invention includes: a line quality detecting step of detecting a line quality between a base station and a mobile station; and a free space and detection of a buffer for temporarily storing a packet transmitted from the base station to the mobile station. A priority calculating step of calculating a priority of the packet used when performing packet transmission scheduling based on the determined channel quality.
[0028]
According to these methods, by reflecting the buffer remaining amount to the priority, the packet data can be preferentially transmitted to a queue having a large amount of data stored in the queue. By transmitting the packet data in the queue before the number of packets reaches, the total buffer amount can be reduced. Furthermore, by considering channel quality, transmission can be preferentially assigned to UEs with good propagation characteristics, so that the throughput of the communication system can be increased. However, for UEs that are not allocated due to poor propagation characteristics or have a large permissible time limit and that have a large amount of packet data stored in the queue, priority is given to transmission by taking into account the remaining buffer capacity. Can be assigned, and the fairness among users can be improved as compared with the case where the priority is calculated only by the channel quality.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
In the flow control, information about the data storage status of the queue is notified from the base station to the RNC, and the amount of data stored in the queue in the base station is controlled by controlling the amount of data transmitted to the base station by the RNC based on this information. Control the amount. However, as shown in FIG. 1, in order to control the amount of data stored in the queue in the base station, it is necessary to control not only the amount of input data from the RNC but also the amount of output data to the UE. Good, or both. The present inventor has paid attention to this point, and has found that by performing packet transmission scheduling in consideration of the data storage state of the queue, the amount of data output to the UE can be controlled, and the amount of data stored in the queue can be controlled. The present invention has been made.
[0030]
In other words, the gist of the present invention is to subtract the buffer capacity in which data is stored from the free capacity of the priority queue for temporarily storing packet data, that is, the total capacity of the queue specified in advance (the specified queue capacity). That is, the priority used in the packet transmission scheduling is determined based on the value (the remaining buffer value). This is equivalent to the fact that packet transmission scheduling plays a part of flow control. Another major feature is that this control can be performed without depending on the upper station.
[0031]
In addition, priority is uniformly determined for both best effort (BE) data and data considering QoS (Quality of Service), and packets stored in a queue with a small remaining buffer amount are transmitted with priority. Therefore, it is possible to reduce the influence of the time lag of the flow control in the upper station.
[0032]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Here, a communication system adopting the HSDPA method will be described as an example, but the base station apparatus and the packet transmission scheduling method of the present invention are not limited to this, and other similar communication systems that perform packet scheduling Is also applicable.
[0033]
(Embodiment 1)
FIG. 2 is a block diagram showing an example of a configuration of the base station apparatus according to Embodiment 1 of the present invention. Here, a case will be described as an example where the base station apparatus receives transmission data from an upper-level station (RNC; Radio Network Controller) 101, performs scheduling, and communicates with a mobile station (UE; User Equipment) 106. Of the dotted lines in the drawing, Iub represents an interface between the upper station and the base station, and Uu represents an interface between the base station and the mobile station.
[0034]
The base station apparatus illustrated in FIG. 2 includes a MAC-hs (Medium Access Control used for high speed) unit 102, a modulation unit 103, a radio transmission / reception unit 104, an antenna 105, and a demodulation unit 107. The MAC-hs unit 102 includes a priority queue (queue with priority) 111, a buffer remaining amount measuring unit 112, a scheduler 113, a switch 114, a TB (transport block) creating unit 115, and an HARQ unit 116. . Here, the priority queue 111 has a circuit corresponding to the number of mobile stations that can be managed by this base station apparatus.
[0035]
In the MAC-hs unit 102, the priority queue 111 receives packet data to be transmitted to the mobile station (UE) 106 from the RNC 101 via Iub. Then, the transmission packet data is stored in a plurality of queues provided for each priority class (service class) of each transmission data. This priority class is notified from the RNC 101 at the same time as the transmission data.
[0036]
The buffer remaining amount measuring unit 112 measures the buffer remaining amount of the queue for each QoS and notifies the scheduler 113 of the measurement.
[0037]
The scheduler 113 calculates a priority for each queue using the remaining buffer value output from the remaining buffer measuring unit 112, selects a queue having the highest priority, and outputs the selected queue to the switch 114. The queue to which the packet has been output is updated with the remaining buffer value. Then, the scheduler 113 determines transmission conditions such as a modulation scheme and a coding rate according to the obtained priority, and uses the control signals C11, C12, C13, C14, and C15 to generate the TB creation unit 115, the HARQ unit, and the like. 116, the modulation section 103, and the radio transmission / reception section 104, respectively. The internal configuration of the scheduler 113 will be described later.
[0038]
The switch 114 selects an output terminal corresponding to the queue selected by the scheduler 113 from a plurality of output terminals corresponding to each queue of the priority queue 111, and switches a packet output from the priority queue 111.
[0039]
The TB creating unit 115 transmits a plurality of packets as a unit according to the TB size specified by the control signal C11 output from the scheduler 113 from the packets output from the priority queue 111 via the switch 114. A TB, which is a unit, is created and output to HARQ section 116.
[0040]
HARQ section 116 outputs the TB (transmission data) output from TB creating section 115 to modulation section 103 while controlling encoding and retransmission according to control signal C12. When the NACK signal is received and the retransmission is waited, the retransmission waiting packet is temporarily stored in a buffer in the HARQ, and when the transmission order comes, the retransmission of the packet is given top priority and transmitted immediately. In the HARQ process, when all packets that can be transmitted are in a transmission waiting state, the processing after the above-described priority calculation is stopped.
[0041]
Modulating section 103 performs modulation processing on the transmission data output from HARQ section 116 using the modulation method specified by control signal C13, and performs coding processing using the number of codes specified by control signal C14. Output to wireless transmission / reception section 104.
[0042]
Radio transmitting / receiving section 104 performs predetermined radio transmission processing such as up-conversion on the modulated transmission data output from modulation section 103, and transmits the data via antenna 105. Further, a signal received via the antenna 105 is subjected to predetermined radio reception processing such as down-conversion and output to the demodulation unit 107.
[0043]
Demodulation section 107 performs demodulation processing on the reception data output from wireless transmission / reception section 104 to obtain reception data. Further, the mobile station extracts reception quality on the mobile station side from the reception data and outputs it to the scheduler 113.
[0044]
FIG. 3 is a diagram showing the concept of the data structure of the priority queue 111.
[0045]
The priority queue 111 has a priority queue 111-1 corresponding to UE # 1 and a priority queue 111-2 corresponding to UE # 2. Then, in the priority queue corresponding to each UE, four queues # 1 to # 4 corresponding to QoS, that is, from a service that requires strict real-time performance to a BE-type service, are installed. The transmitted packets are classified and stored in respective queues. Here, the CIR of UE # i is CIR # 1, and the remaining buffer value of queue #j of UE # i is q_ij, The priority of the packet stored in the queue #j of the UE #i is P_ijAnd Note that the configuration of the priority queue 111 is not limited to this, and it is possible to perform processing of two or more mobile stations, and the number of queues is not limited to four.
[0046]
The scheduler 113 assigns the priority P to each of the priority queues 111._ijIs calculated, and the queue having the highest priority is selected. In the next TTI (Transmission Timing Interval), the buffer remaining value is updated for the queue in which the packet was transmitted in the current TTI or the queue in which the packet was transmitted from the upper station. Other queues hold the current buffer remaining value.
[0047]
FIG. 4 is a block diagram illustrating an example of the internal configuration of the scheduler 113. The scheduler 113 has a reception quality detection unit 121, a priority calculation unit 122, a queue selection unit 123, and a transmission control unit 124.
[0048]
Reception quality detection section 121 detects reception quality from CQI (Channel Quality Indicator), which is channel quality information on the mobile station side extracted from the reception data demodulated by demodulation section 107. The CQI is information for notifying a base station in communication of a transmission rate that the mobile station can receive and the like, and is determined based on reception quality at the mobile station. Here, the reception quality used on the base station side may be an estimated CIR or the like, or a CQI value of 30 steps may be directly used.
[0049]
As the channel quality information, in addition to CQI based on CIR (Carrier to Interference Ratio) of a common pilot channel (CPICH; Common Pilot Channel) measured by a mobile station, A-DPCH (Associated) that is transmission power controlled -Dedicated Physical Channel transmission power or the like can be used. The transmission power can be used because if the reception quality of the mobile station is poor, the transmission power of the base station also increases according to the request of the mobile station.
[0050]
The priority calculating unit 122 is notified of the remaining buffer value from the remaining buffer measuring unit 112. And
Priority = reception quality x 1 / remaining buffer value
The priority is calculated for each queue according to the following formula, and is output to the queue selection unit 123. Specifically, the above CIR # i, q_ij, P_ijUsing,
P_ij  = CIR # i x 1 / q_ij
It is expressed as
[0051]
The queue selection unit 123 selects the queue having the highest priority and notifies the switch 114 and the transmission control unit 124.
[0052]
The transmission control unit 124 is notified of the reception quality from the reception quality detection unit 121, the ACK / NACK signal from the demodulation unit 107, and the selected queue from the queue selection unit 123. The transmission condition, that is, the TB size, HARQ retransmission control, modulation scheme, and transmission power are determined based on the queue selected by the queue selection unit 123, and the TB control signal C11 is transmitted to the TB creation unit 115, and the transmission A retransmission control signal C12, a modulation control signal C13 and an encoding control signal C14 are sent to the modulation section 103, and a transmission power control signal C15 is sent to the radio transmission / reception section 104 to control each circuit.
[0053]
FIG. 5 is a flowchart summarizing the procedure of the packet transmission scheduling method used by the base station apparatus.
[0054]
The base station apparatus according to the present embodiment receives a transmission packet from RNC 101 (ST1010) and stores it in priority queue 111 (ST1020). Then, the remaining buffer capacity is measured (ST1030). On the other hand, the signal transmitted from UE 106 is received by antenna 105 (ST 1050), and radio transmission / reception section 104 performs radio reception processing (ST 1060). Next, demodulation section 107 demodulates the received data (ST1070), and detects information related to the reception quality on the mobile station side from the data (ST1080).
[0055]
After obtaining the remaining buffer value and the reception quality, the scheduler 113 calculates the priority of the transmission packet (ST1090), determines the packet to be actually transmitted, and then determines the transmission condition for the transmission packet (ST1090). ST1100). Then, based on this transmission condition, the base station apparatus transmits a transmission packet to the mobile station (ST1110).
[0056]
FIG. 6 is a diagram illustrating the effect of the present embodiment realized by the above configuration.
[0057]
When viewed from the queue of the base station, in an excessive input situation (when the input data amount is larger than the output data amount), the data storage amount in the queue rises to the right with time as shown by a dotted line C1 in the figure. It rises (it is not necessarily a straight line as shown in the figure). Under this circumstance, conventionally, when the upper limit of the buffer amount of the queue is level L2, the packet transmitted to the base station when the data storage amount in the queue exceeds this level is discarded. . Also, for example, when the base station notifies the upper station to narrow down the input when the data storage amount exceeds the threshold L3, as described above, there is a time lag until the input is actually reduced. Assuming that the data storage amount at the time when the number of inputs actually decreases is L1, a buffer for absorbing the data increase amount (L1-L2) during that time is required. However, the flow control method is not limited to the above method.
[0058]
In the present embodiment, packet transmission scheduling is performed in accordance with the data storage amount (remaining buffer amount) of the queue, so that the output as viewed from the base station increases. As a result, the data storage amount becomes the solid line C2 The behavior shown in FIG. Therefore, the data storage amount rarely exceeds the upper limit level L2, and the necessity of providing an extra buffer of (L1−L2) is small. Therefore, according to the present embodiment, it is possible to appropriately control the amount of data stored in the queue and to reduce unnecessary buffers.
[0059]
In the above configuration, the scheduler 113 determines the priority at the time of packet transmission for a packet belonging to any priority class by a single method. Specifically, the priority calculation unit 122 determines the priority based on the remaining buffer capacity and the reception quality.
[0060]
As described above, according to the present embodiment, the MAC-hs unit 102 reflects the remaining buffer amount in the priority, thereby reducing an extra memory in consideration of a time lag in the exchange of control information with the upper station. it can. Further, the amount of data stored in each queue can be averaged. Further, by considering the line quality, the throughput of the communication system can be increased.
[0061]
Here, the case where transmission data is transmitted from the upper station (RNC) has been described as an example, but in the case of a network having a non-hierarchical structure such as the Internet, transmission data is transmitted from a router.
[0062]
Further, here, the case where the priority is determined based on both the reception quality and the remaining buffer capacity has been described as an example, but a mode in which the priority is determined based only on the remaining buffer capacity may be considered.
[0063]
(Embodiment 2)
FIG. 7 is a block diagram showing an example of a configuration of the base station apparatus according to Embodiment 2 of the present invention. This base station apparatus has the same basic configuration as the base station apparatus shown in FIG. 2, and the same components are denoted by the same reference numerals and description thereof will be omitted.
[0064]
A feature of the present embodiment is that a timer 201 is further provided, and scheduling is further performed in consideration of the remaining time with respect to the permissible transmission delay time, whereby priority can be uniformly determined.
[0065]
In the MAC-hs unit 102, each queue of the priority queue 111 has an allowable transmission delay time T_LIs stipulated. Then, the priority queue 111 stores the packet at the storage time t._SAnd the specified time T_LTo the timer 201 for each packet.
[0066]
The timer 201 has a timer corresponding to each packet data, and outputs a remaining time (remaining time) in which the packet data can remain in the priority queue 111 to the scheduler 113a. Note that packet data may be grouped and a timer may be provided for each group. As an initial value of the timer, a specified time of a queue in which a packet is stored is set, and the remaining time is decremented as time elapses.
[0067]
FIG. 8 is a diagram showing the concept of the data structure of the priority queue 111. Buffer remaining amount q_ij, The received product CIR # i of the signal received by the mobile station, and the permissible delay time t_ijPriority calculation is performed on the basis of to determine the priority. Each queue has a specified time T based on the allowable delay time._LIs defined. Specified time T for services with strong real-time properties_LIs set shorter, whereas the specified time is set longer as the BE service is approached. Note that the remaining time of the packet that has not been transmitted is not reset in the next TTI.
[0068]
If the priority class is BE, the specified time T_LIs not decremented, and the remaining time is constant. At this time, as the specified time, a value equal to or less than the value indicating the maximum value among all the specified times already specified in the other queues is automatically set. Note that the allowable delay time of the packet may be set directly.
[0069]
The scheduler 113a uses the remaining time output from the timer 201 in the priority calculation unit 122a, the reception quality of the signal received by the mobile station, and the remaining buffer value as shown in FIG.
Priority = reception quality x 1 / remaining buffer value x 1 / remaining time
The priority is calculated for each of the oldest packets stored in each queue according to the following formula, and the queue storing the packet with the highest priority is selected and notified to the switch 114 and the transmission control unit 124. I do. Specifically, the above P_ij, CIR # i, q_ij, T_ijUsing,
P_ij  = CIR # i x 1 / q_ij  × 1 / t_ij
Is represented as
[0070]
However, the calculation for obtaining the remaining time is performed for all packets stored in each queue. Then, the scheduler 113a performs control in the same manner as before according to the obtained priority.
[0071]
Also, in the HARQ process, an example has been described in which, when a NACK signal is received and a retransmission wait is received, a packet in the HARQ is temporarily stored in a buffer in the HARQ and retransmitted immediately when a transmission order comes. However, when waiting for retransmission, the priority calculation may be performed again to retransmit the packet. In this case, the timer value of the packet waiting to be retransmitted continues to measure the remaining time similarly to the timer values of the other packets, and the priorities including the other packets are compared. However, even if a packet to be retransmitted is selected, if the packet is still in the retransmission waiting state, the process does not shift to the transmission process. At this time, the scheduler 113a calculates the priority of the packet data stored next to the same queue.
[0072]
By using the above equation, in addition to the effect of the first embodiment, since the priority is set higher for packets having a smaller remaining time, QoS can be guaranteed, and the reciprocal of the remaining time is used. When the remaining time approaches 0, the priority is set to be extremely high, and the allowable delay time can be kept. In addition, since the priority in consideration of QoS can be uniformly determined by a simple algorithm, it is possible to reduce the processing calculation amount and the processing time of the packet transmission scheduling.
[0073]
(Embodiment 3)
FIG. 10 is a block diagram showing an example of a configuration of a base station apparatus according to Embodiment 3 of the present invention. Note that this base station apparatus has the same basic configuration as the base station apparatus shown in FIG. 7, and the same components are denoted by the same reference numerals and description thereof will be omitted.
[0074]
A feature of the present embodiment is that it further has a throughput calculation unit 301, and the scheduler 113b determines the priority in consideration of the actual throughput of the mobile station.
[0075]
The throughput calculation unit 301 monitors the output of the demodulation unit 107, calculates the actual throughput when the mobile station transmits data to the base station, and outputs the calculated throughput to the scheduler 113b. As the actual throughput, an average value in a predetermined period may be used, or another parameter indicating the same concept may be used.
[0076]
The scheduler 113b outputs the remaining buffer value output from the remaining buffer measuring unit 112, the remaining time output from the timer 201, the reception quality of the mobile station output from the demodulating unit 107, and the output from the throughput calculating unit 301. Using the actual throughput
Priority = reception quality x 1 / remaining buffer value x 1 / remaining time x 1 / actual throughput
The priority is calculated for each packet according to the following equation.
[0077]
The scheduler 113b also performs transmission control as in the first embodiment. The difference from the first embodiment is that the TB control signal C11 is also sent to the throughput calculation unit 301, and the throughput calculation unit 301 calculates the throughput using the TB size notified by the control signal.
[0078]
FIG. 11 is a diagram showing the concept of the data structure of the priority queue 111. Buffer remaining amount q_ij, Received signal CIR # i of the signal received by the mobile station, allowable delay time t_ij, And actual throughput Th_ijPriority P based on_ijIs
P_ij  = CIR # i x 1 / q_ij  × 1 / t_ij  × 1 / Th_ij
Is represented by
[0079]
FIG. 12 is a block diagram illustrating an example of the internal configuration of the scheduler 113b. The actual throughput output from the throughput calculation unit 301 is input to the priority calculation unit 122b, and the priority is calculated as in the first embodiment. However, the reception quality is calculated for each UE, and the throughput is calculated for each queue.
[0080]
In the above configuration, the priority calculation unit 122b in the scheduler 113b calculates the priority based on the above equation, so that in addition to the effects of the first and second embodiments, the same effect as the PF method is expected. can do. This is because the (reception quality x 1 / actual throughput) portion of the above equation is the same as the metric in the PF scheme.
[0081]
As described above, according to the present embodiment, extra memory can be reduced and scheduling can be performed in a unified manner, so that the amount of processing calculations and processing time for scheduling in packet control can be reduced, and communication can be reduced. It is possible to increase the throughput of the system, and to achieve the same effect as the PF method in which transmission opportunities are allocated in consideration of fairness of throughput while considering channel quality.
[0082]
(Embodiment 4)
The base station apparatus according to Embodiment 4 of the present invention has the same basic configuration as base station apparatus shown in FIG. Therefore, the same components are denoted by the same reference numerals, and description thereof will be omitted.
[0083]
A feature of the present embodiment is that a memory 401 is further provided inside the scheduler 113c. FIG. 13 is a block diagram illustrating an example of the internal configuration of the scheduler 113c.
[0084]
In the scheduler 113c, the memory 401 outputs the stored coefficients α, β, and γ to the priority calculation unit 122c. The values of α, β, and γ will be described later.
[0085]
The priority calculation unit 122c calculates the remaining buffer value output from the remaining buffer measurement unit 112, the remaining time output from the timer 201, the reception quality of the mobile station output from the demodulation unit 107, and the throughput calculation unit 301 Using the output actual throughput and the coefficients α, β, and γ output from the memory 401,
Priority = Reception quality × (α × 1 / buffer remaining value) × (β × 1 / remaining time) × (γ × 1 / actual throughput)
The priority is calculated for each packet according to the following equation.
[0086]
Here, α, β, and γ are coefficients for the purpose of weighting the remaining buffer value, the remaining time, and the actual throughput in the above equation. For example, if the throughput requested by the mobile station to the base station differs depending on the type of packet (service), a value corresponding to the type of packet is set in γ, and the priority is weighted in advance according to the type of packet. Can be. Further, for example, considering the condition that the throughput required by the mobile station does not have to be satisfied in some cases, but always wants to observe the specified time, the priority is set by setting a value larger than β compared to γ. In the calculation of, the contribution of the remaining time increases, and as a result, the priority with the specified time being emphasized is calculated. Conversely, when it is desired to increase the throughput for BE packets with a large specified allowable time, or for services such as FTP, which have a large data speed variance such that a large number of packets are sent from the upper layer at one time. By setting the value of α larger than β and γ, it is possible to determine the priority with emphasis on the remaining buffer capacity.
[0087]
As described above, according to the present embodiment, in order to calculate the priority by weighting the remaining buffer value, the remaining time, and the actual throughput, by setting the ratio to an appropriate value in consideration of the weighting ratio, Thus, it is possible to perform an appropriate priority calculation according to the situation.
[0088]
Note that, here, the case where the specified time is set to a different value according to the priority class has been described as an example, but according to the above equation, all the specified times are set to the same value. Different values can be set for the above β depending on the priority class.
[0089]
Note that the weight coefficients of α, β, and γ may be set by signaling from a higher-level device. In addition, the time may be changed by the base station depending on the traffic condition or the like.
[0090]
Also, in the first to fourth embodiments, the case where the priority calculation in the packet transmission scheduling is performed based on the remaining buffer capacity is described, but the priority is stored in the buffer instead of the remaining buffer capacity. The data amount (storage data amount) may be used. That is, for example, in the expression for obtaining the priority in the first embodiment, since the magnitude relation is reversed,
Priority = reception quality x stored data amount
Becomes The same applies to other embodiments. As a result, packets stored in the queue having a large amount of stored data can be transmitted with priority.
[0091]
Further, the expressions for obtaining the priority are all multiplications, but the present invention is not limited to this. For example, the priority may be obtained by addition.
[0092]
【The invention's effect】
As described above, according to the present invention, it is possible to preferentially transmit packet data to a queue having a large amount of data stored in the queue by reflecting the buffer remaining amount in the priority, By transmitting packet data in the queue before reaching the upper limit of the specified queue amount, the total buffer amount can be reduced. In addition, transmission can be preferentially allocated to UEs that are not allocated due to poor propagation characteristics or a large permissible prescribed time and that have a large amount of packet data stored in the queue. Can be improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing an input / output relationship with a queue in a base station.
FIG. 2 is a block diagram showing an example of a configuration of a base station apparatus according to Embodiment 1 of the present invention.
FIG. 3 is a diagram showing a concept of a data structure of a priority queue according to the first embodiment of the present invention.
FIG. 4 is a block diagram showing an example of an internal configuration of a scheduler according to Embodiment 1 of the present invention.
FIG. 5 is a flowchart summarizing procedures of a packet transmission scheduling method used by the base station apparatus according to Embodiment 1 of the present invention.
FIG. 6 is a diagram illustrating an effect of the first embodiment of the present invention.
FIG. 7 is a block diagram showing an example of a configuration of a base station apparatus according to Embodiment 2 of the present invention.
FIG. 8 is a diagram showing a concept of a data structure of a priority queue according to the second embodiment of the present invention.
FIG. 9 is a block diagram showing an example of an internal configuration of a scheduler according to Embodiment 2 of the present invention.
FIG. 10 is a block diagram showing an example of a configuration of a base station apparatus according to Embodiment 3 of the present invention.
FIG. 11 is a diagram showing a concept of a data structure of a priority queue according to the third embodiment of the present invention.
FIG. 12 is a block diagram showing an example of an internal configuration of a scheduler according to Embodiment 3 of the present invention.
FIG. 13 is a block diagram showing an example of an internal configuration of a scheduler according to Embodiment 4 of the present invention.
[Explanation of symbols]
101 Upper station (RNC)
106 mobile station (UE)
111 priority queue
112 Buffer remaining amount measurement unit
113, 113a, 113b, 113c Scheduler
114 switch
121 reception quality detection unit
122, 122a, 122b, 122c Priority operation unit
123 Queue Selector
201 timer
301 Throughput calculator
401 memory

Claims (11)

A base station that performs packet transmission scheduling when transmitting a packet to a mobile station,
A buffer for temporarily storing packets to be transmitted to the mobile station,
Based on the free space of the buffer, priority calculation means for calculating the priority of the packet used when performing the packet transmission scheduling,
A base station device comprising: A base station that performs packet transmission scheduling when transmitting a packet to a mobile station,
A buffer for temporarily storing packets to be transmitted to the mobile station,
Line quality acquiring means for acquiring the line quality between the own station and the mobile station,
Based on the free space of the buffer and the acquired line quality, priority calculation means for calculating the priority of the packet used when performing the packet transmission scheduling,
A base station device comprising: The priority calculating means,
Calculating the priority of the packet further based on the remaining time for the transmission allowable delay time of the packet,
The base station apparatus according to claim 1 or 2, wherein: The priority calculating means,
Calculating the priority of the packet further based on the throughput of the line between the own station and the mobile station,
The base station apparatus according to claim 1 or 2, wherein: The priority calculating means,
Calculating a higher priority of the packet as the free space of the buffer is smaller,
The base station apparatus according to any one of claims 1 to 4, wherein: The priority calculating means,
Calculating the priority of the packet exponentially higher as the free space of the buffer is closer to 0;
The base station apparatus according to any one of claims 1 to 4, wherein: The priority calculating means,
Calculating the priority of the packet using the ratio of the free space of the buffer and the obtained line quality,
The base station apparatus according to any one of claims 2 to 4, wherein: Weighting means for weighting the free space of the buffer,
The priority calculating means,
Calculating the priority of the packet based on the weighted free space of the buffer,
The base station apparatus according to any one of claims 2 to 4, wherein: The priority calculating means,
Calculating the priority of the packet based on the amount of data stored in the buffer instead of the free space of the buffer,
The base station apparatus according to any one of claims 1 to 8, wherein: A priority calculating step of calculating a priority of the packet used when performing packet transmission scheduling based on a free space of a buffer for temporarily storing a packet transmitted from the base station to the mobile station. Characteristic packet transmission scheduling method. A line quality detecting step of detecting a line quality between the base station and the mobile station;
Priority for calculating the priority of the packet used when performing packet transmission scheduling based on the free space of a buffer for temporarily storing a packet transmitted from the base station to the mobile station and the detected channel quality A degree calculation step;
A packet transmission scheduling method, comprising:

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